Many manufacturing processes require delivery of relatively high purity gases at regulated flow rates and pressures. In the manufacture of semiconductors, for example, the purity and flow rate of a gas must be carefully regulated to prevent defects on a wafer. The loss of a wafer due to a defect is both expensive and time consuming.
In semiconductor manufacturing, gas is provided to a process chamber through a “gas stick.” A gas stick can include a variety of components such as filters, valves, mass flow controllers, pressure transducers or other components to purify the gas, regulate gas flow or monitor properties of the gas or gas flow. Traditionally, components were connected in an “in-line” fashion with each component connected to the next component by a VCR connector. More recently, the semiconductor industry has moved to modular architectures. In a modular architecture, the gas components mount to modular substrate blocks. Flow passages in the substrate blocks route flow between the substrate blocks and hence the gas components. Modular architectures provide the advantage of a reduced footprint and standardization of interfaces.
FIG. 1 illustrates one embodiment of a gas stick 100 using a modular architecture. In the example of FIG. 1, pressure transducer 102 is mounted on substrate block 104 and filter 106 is mounted on substrate block 108. Gas stick 100 requires substrate 108 to accommodate the standalone filter 106. The additional substrate 108 makes gas stick 100 longer, heavier and more expensive.
Several attempts have been made to shorten the gas stick by using a stackable filter. Prior filters have been made that have a purification element sandwiched between two sections of a block or purification elements vertically aligned with the various flow passages to/from the substrate or components stacked on top of the filter. The first type of filter suffers the disadvantage of requiring multiple seals between various sections of the filter block. The additional mechanical seals can interrupt the flow path, increase wetted surface area and increase dead space. Additionally, the seals may leak due to dimensional or surface finish irregularities between the sealing surfaces of the sections of the filter block. The second type of filter (e.g., the filter in which the purification element is aligned with a flow passage), requires additional height to accommodate the purification element.
Consequently, there is a need for a low-profile filter that minimizes mechanical seals, gas stick length and height while fitting the footprint of modular substrates.